KR20200002797A - Distance sensor for measuring distance to ferromagnetic element, magnetic levitation system, and method for measuring distance to ferromagnetic element - Google Patents

Abstract

The present disclosure relates to a distance sensor for measuring the distance to a ferromagnetic element, a magnetic levitation system for magnetically floating a ferromagnetic element, and a method for compensating floating magnetic fields in the distance sensor. According to a first aspect, a distance sensor for measuring the distance to a ferromagnetic element is provided. According to a second aspect, a magnetic levitation system for magnetic levitation of a ferromagnetic element is provided, the magnetic levitation system comprising at least one electromagnetic actuator and at least one distance sensor according to the first aspect, the at least one distance sensor Is configured to measure the distance to the ferromagnetic element. According to a third aspect, a method is provided for measuring a distance to a ferromagnetic element, the method comprising: providing a distance sensor comprising a first hall element and a second hall element, a first signal of the first hall element And detecting a second signal of the second Hall element, and subtracting the second signal from the first signal. According to a fourth embodiment, the use of a distance sensor according to the first aspect is provided, wherein the distance sensor is used in a magnetically levitated device and the distance sensor is configured to measure the distance to the injured body.

Description

Distance sensor for measuring distance to ferromagnetic element, magnetic levitation system, and method for measuring distance to ferromagnetic element

[0001] Embodiments of the present disclosure relate to a distance sensor for measuring the distance to a ferromagnetic element. More specifically, embodiments of the present disclosure relate, in particular, to a magnetic levitation system for magnetically levitating a ferromagnetic element, and a method for compensating floating magnetic fields in a distance sensor.

[0002] Various processes are known for performing the coating of a substrate in a processing chamber, for example. Several methods are known for depositing a material onto a substrate. For example, substrates may use an evaporation process, a physical vapor deposition (PVD) process, such as a sputtering process, a spraying process, or the like, or a chemical vapor deposition (CVD) process. Can be coated. The process can be performed in the processing chamber of the deposition apparatus in which the substrate to be coated is located. Deposition material is provided to the processing chamber. A plurality of materials, such as small molecules, metals, oxides, nitrides and carbides, can be used for deposition on the substrate. In addition, other processes such as etching, structuring, annealing, and the like may be performed in the processing chambers.

[0003] For example, coating processes may be considered for large area substrates, such as in display manufacturing techniques. Coated substrates may be used in many applications and in various technical fields. For example, the application may be organic light emitting diode (OLED) panels. Further applications include insulating panels, microelectronics such as semiconductor devices, substrates with thin film transistors (TFTs), color filters, and the like. OLEDs are solid-state devices made of thin films of (organic) molecules that produce light by the application of electricity. By way of example, OLED displays can provide bright displays on electronic devices, for example, using reduced power compared to liquid crystal displays (LCDs). In the processing chamber, organic molecules are produced (eg, evaporated, sputtered, or sprayed, etc.) and deposited as layers on the substrates. The particles may pass through a mask having a boundary or a specific pattern, for example to deposit material at specific positions on the substrate, such as to form an OLED pattern on the substrate.

[0004] The processing system may include a magnetic levitation system for guiding the carrier in the processing chamber, for example during the coating process. The magnetic levitation system may be adapted to transport the carrier within the processing chamber and / or to provide the carrier to the processing position. The magnetic levitation system can include one or more levitation units with electromagnetic actuators, sensors, signal processors and power amplifiers to form a closed control loop such that the levitation carrier can be removed from the magnetic bearing. It is kept at a predetermined distance.

[0005] In applications where substrates are processed in high vacuum, metallic shielding of actuators, sensors, and other components prevents the use of some types of distance sensors. In such applications, distance sensors based on magnetic effects, such as hall effect sensors, are used because they can measure distances through non-ferrous metallic shielding. to be.

[0006] One aspect of the magnetic levitation system is to move electromagnetic actuators and distance sensors closer to each other in the levitation unit to achieve a minimized size of the magnetic levitation system and improved control behavior through colocation of the actuator and sensor. Positioning.

[0007] In view of the above, an aspect of the present disclosure is to provide a distance sensor and a method for operation of the distance sensor that overcome at least some of the problems in the art.

[0008] According to a first embodiment, a distance sensor for measuring the distance to a ferromagnetic element is provided. The distance sensor includes at least a first permanent magnet element, at least a first hall element, and at least a second hall element, wherein the first permanent magnet element generates a first magnetic field, and the first in the position of the first hall element. The direction of the magnetic field is substantially opposite to the direction of the first magnetic field at the position of the second hole element.

[0009] According to a second embodiment, a magnetic levitation system for magnetic levitation of a ferromagnetic element is provided. The magnetic levitation system comprises at least one electromagnetic actuator and at least one distance sensor according to the first embodiment, wherein the at least one distance sensor is configured to measure the distance to the ferromagnetic element.

[0010] According to a third embodiment, a method for measuring the distance to a ferromagnetic element is provided. The method includes providing a distance sensor comprising a first Hall element and a second Hall element, detecting a first signal of the first Hall element and a second signal of the second Hall element, and from the first signal; Subtracting two signals.

[0011] According to a fourth embodiment, the use of the distance sensor according to the first embodiment is provided. The distance sensor is used in a magnetically levitated device, and the distance sensor is configured to measure the distance to the injured body.

[0012] Embodiments also relate to apparatuses for performing the disclosed methods and include apparatus portions for performing each described method step. These method steps may be performed by hardware components, by a computer programmed by appropriate software, by any combination of the two, or in any other manner. In addition, embodiments according to the present disclosure also relate to methods of operating the described apparatus. The method includes method steps for performing all respective functions of the apparatus.

In a manner in which the above-listed features of the present disclosure may be understood in detail, a more specific description of the disclosure briefly summarized above may be made with reference to the embodiments. The accompanying drawings relate to embodiments of the present disclosure and are described below:
1 shows a schematic front view of a magnetic levitation system in accordance with embodiments described herein;
2A shows a cross-sectional side view of a magnetic levitation system in accordance with embodiments described herein;
2B shows a front cross-sectional view of a magnetic levitation system in accordance with embodiments described herein;
3A, 3B show side cross-sectional views of a distance sensor in accordance with embodiments described herein;
4 shows a flowchart of a method for measuring a distance to a ferromagnetic element, in accordance with embodiments described herein; And
5 shows a flowchart of a method for further compensation of an erroneous component of a distance signal in accordance with embodiments described herein.

[0014] Reference will now be made in detail to various embodiments of the present disclosure, in which one or more examples of various embodiments are illustrated in the drawings. Within the following description of the drawings, like reference numerals refer to like components. In general, only differences to individual embodiments are described. Each example is provided by way of explanation of the disclosure and is not intended as a limitation of the disclosure. In addition, features illustrated or described as part of one embodiment may be used with or with other embodiments to yield another additional embodiment. The description is intended to include such modifications and variations.

[0015] Embodiments described herein involve magnetic levitation and / or transfer of a carrier, such as a substrate carrier. Thus, the magnetic levitation of the carrier can be contactless. The term "contactless" as used throughout the present disclosure may be understood to mean that the weight of the carrier is held by magnetic force rather than by mechanical contact or mechanical forces. Specifically, the carrier can be held in a floating or floating state using magnetic forces instead of mechanical forces. In some implementations, there can be no mechanical contact between the carrier and the rest of the device during movement of the carrier and eg during movement.

[0016] Compared with mechanical devices for guiding the carrier in the processing system, the advantage is that the non-contact injury is not affected from friction which affects the precision and / or linearity of the carrier's movement. Non-contact transfer of the carrier allows for frictionless movement of the carrier, for example the position of the carrier relative to the mask in the deposition process can be controlled and maintained with high precision. Injuries also allow for rapid acceleration or deceleration of the carrier, and / or precise adjustment of the carrier speed.

[0017] For example, non-contact floating or conveying of the carrier during the deposition process is advantageous in that no particles are produced due to mechanical contact between the sections of the device during the transport of the carrier, such as mechanical rails and the carrier. Thus, non-contact magnetic levitation systems provide improved purity and uniformity of the layers deposited on the substrate, especially when particle generation is minimized when using non-contact magnetic levitation.

[0018] The magnetic levitation system can be configured to operate in a vacuum environment. The processing system may include at least one vacuum chamber and the deposition process is performed on the substrate. The at least one vacuum chamber may comprise one or more vacuum pumps, such as turbo pumps and / or cryo-pumps, connected to the vacuum chamber for the creation of a vacuum inside the vacuum chamber. The magnetic levitation system may be configured to transfer the substrate into, out of, or through the vacuum chamber.

[0019] The magnetic levitation system can be used to transport the carrier. The carrier may be adapted to carry a substrate, a plurality of substrates and / or a mask. The carrier may be, for example, a substrate carrier adapted to carry a large area substrate and / or a plurality of large area substrates. Alternatively, the carrier may be a mask carrier adapted to carry an edge exclusion mask, for example, to prevent the edges of the substrate from being coated in the deposition process.

[0020] The carrier according to the embodiments described herein need not be limited to a substrate carrier or a mask carrier. The methods described herein also apply to other types of carriers, ie carriers adapted to carry objects or devices other than, for example, substrates or masks.

[0021] As used herein, the term "substrate" includes both flexible substrates, such as webs or foils, and glass plates, or slices of transparent crystals, such as glass substrates, wafers, sapphires, and the like. . According to embodiments that can be combined with other embodiments described herein, the embodiments described herein can be utilized for sputter deposition on display PVD, ie large area substrates for the display market.

[0022] According to embodiments, the large area substrate or the individual carrier may have a size of at least 0.67 m 2. The size may be between about 0.67 m 2 (0.73 × 0.92 m—Gen 4.5) to about 8 m 2, more specifically between about 2 m 2 and about 9 m 2 or even up to 12 m 2. For example, a large area substrate or carrier may comprise GEN 4.5 corresponding to approximately 0.67 m 2 substrates (0.73 × 0.92 m), GEN 5 corresponding to approximately 1.4 m 2 substrates (1.1 m × 1.3 m), approximately 4.29 m 2 substrates ( GEN 7.5 corresponding to 1.95 m × 2.2 m), GEN 8.5 corresponding to approximately 5.7 m 2 substrates (2.2 m × 2.5 m), or even GEN 10 corresponding to approximately 8.7 m 2 substrates (2.85 m × 3.05 m) Can be. Even larger generations and corresponding substrate areas such as GEN 11 and GEN 12 can be similarly implemented.

[0023] The figures show the carrier oriented vertically. As exemplarily shown in FIG. 1, the carrier 110 supporting the substrate 120 is oriented in a plane defined by the first direction 192 and the second direction 194, and the first direction 192. ) Is substantially oriented in the carrier transport direction, and the second direction 194 is oriented substantially parallel to the direction of gravity. The first direction 192 is oriented substantially perpendicular to the second direction 194. However, the embodiments described herein are not limited to vertically oriented carriers. Other orientations of the carrier, such as horizontal orientation, may also be provided.

[0024] In the present disclosure, the term of “substantially parallel” directions may include directions that form a small angle of up to 10 °, or even up to 15 ° of each other. The term "substantially perpendicular" may include directions that form an angle of less than 90 ° with each other, such as at least 80 ° or at least 75 °. Similar considerations apply to concepts such as substantially parallel or vertical axes, planes, regions, orientations, and the like.

[0025] Some embodiments described herein involve the concept of "vertical direction." The vertical direction is considered to be parallel or substantially parallel to the direction in which gravity extends. The vertical direction may deviate from the exact vertical, for example by an angle of up to 15 ° (the exact vertical is defined by gravity).

[0026] Embodiments described herein may further involve the concept of "horizontal direction". It should be understood that the horizontal direction is distinguished from the vertical direction. The horizontal direction may be perpendicular to the exact vertical direction defined by gravity or may be substantially perpendicular.

[0027] Embodiments described herein relate to a magnetic levitation system for magnetically floating a ferromagnetic element as well as a distance sensor for measuring the distance to the ferromagnetic element. First, reference is made to FIG. 1, which shows an example of a magnetic levitation system 100 in accordance with embodiments described herein.

[0028] The magnetic levitation system 100 shown in FIG. 1 includes a carrier 110. The carrier 110 supports the substrate 120. The carrier 110 includes a ferromagnetic element 150, such as a bar of ferromagnetic material. The magnetic levitation system 100 includes a plurality of levitation units 170 including, for example, active magnetic units, such as electromagnetic devices, solenoids, coils or superconducting magnets. Individual floating units of the plurality of floating units 170 are indicated by reference numeral 175. The plurality of floating units 170 extend in the first direction 192. The carrier 110 is movable along the plurality of floating units 170. The ferromagnetic element 150 and the plurality of floating units 170 are configured to provide a magnetic flotation force for floating the carrier 110. The magnetic levitation force extends in the second direction 194.

[0029] The magnetic levitation system 100 shown in FIG. 1 may include a plurality of distance sensors (not shown) provided in the plurality of levitation units 170. A distance sensor may be provided to each floating unit 175. Alternatively, a distance sensor may be provided within each floating unit 175. The distance sensors may be configured to measure the distances between the plurality of injury units 170 and the carrier 110 during a contactless injury of the carrier 110.

[0030] The magnetic levitation system 100 shown in FIG. 1 includes a magnetic drive structure 180. The magnetic drive structure 180 includes a plurality of magnetic drive units. Individual magnetic drive units of the magnetic drive structure 180 are indicated by reference numeral 185. Carrier 110 may include second ferromagnetic element 160 for interacting with magnetic drive units 185 of magnetic drive structure 180. Magnetic drive units 185 of magnetic drive structure 180 drive a carrier in a processing system, eg, along first direction 192. For example, the second ferromagnetic element 160 may include a plurality of permanent magnets arranged in alternating polarity. The resulting magnetic fields of the second ferromagnetic element 160 interact with the plurality of magnetic drive units 185 of the magnetic drive structure 180 to move the carrier 110 in the first direction 192 in a floating state. Can work.

[0031] The magnetic levitation system 100 includes a control unit 130. The control unit 130 may be connected to the plurality of floating units 170 and / or distance sensors. The control unit 130 can be configured to control the magnetic levitation of the carrier 110. The control unit 130 may, for example, based on the measured distances supplied to the control unit 130 by the distance sensors, during the injury of the carrier 110 and the plurality of magnetic units 170. It can be configured to control the distance between. The magnetic drive structure 180 can drive the carrier 110 under the control of the control unit 130.

[0032] Reference is now made to FIGS. 2A and 2B showing cross sectional views of the floating unit 175. FIG. 2A is a cross sectional view in a first direction 192 or carrier transport direction, and FIG. 2B is a third direction 196 perpendicular to the first direction 192 and second direction 194, or transverse to the carrier transport direction. It is a cross-sectional view in the direction of screaming.

[0033] According to embodiments of the present disclosure, which may be combined with other embodiments described herein, the floating unit 175 includes at least an electromagnetic actuator 178. The electromagnetic actuator 178 can include at least a coil 178a and at least a ferromagnetic core 178b, which generates a magnetic field upon application of current to the coil 178a. The magnetic field generated by the electromagnetic actuator 178 applies a magnetic flotation force to the ferromagnetic element 150 in the second direction 194, causing the carrier 110 to which the ferromagnetic element 150 is attached to float.

[0034] According to embodiments of the present disclosure, which may be combined with other embodiments described herein, at least one electromagnetic actuator, at least one distance sensor and controller may be included in an airtight enclosure. Due to the operation of the magnetic levitation system 100 in high or ultra high vacuum applications, various components of the levitation unit 175 are shielded from the ambient vacuum environment. For this purpose, the floating unit 175 can further include a housing 176, which encloses the components of the floating unit 175 to allow the components of the floating unit 175 to be placed in an ambient vacuum environment. Shield from Housing 176 may be a sealed enclosure that encloses internal volume 177 such that internal volume 177 is separated from the surrounding vacuum environment. Separating the internal volume 177 from the ambient vacuum environment avoids contamination of the ambient vacuum environment.

[0035] The housing 176 can include a non-ferromagnetic material, allowing at least one distance sensor 200 located within the housing 176 to detect a magnetic field through the housing 176. For example, the housing 176 may comprise metal, in particular aluminum alloy or non-ferromagnetic stainless steel.

[0036] Internal volume 177 may be maintained at the same pressure as the surrounding vacuum environment, or at a different pressure than the surrounding vacuum environment. For example, internal volume 177 can be maintained at a higher pressure than the ambient vacuum environment. This feature allows the components of the floating unit 175 included in the housing 176 to be cooled through convection or internal volume 177 so that electrical arcing between the electrical or electronic components included in the housing 176 is avoided. It is possible to modify the mean free path of. In addition, internal volume 177 may contain a gas composition that is the same as or different from the ambient vacuum environment.

[0037] According to embodiments of the present disclosure, which may be combined with other embodiments described herein, the injury unit 175 may further include a controller 179. Controller 179 is electrically attached to at least distance sensor 200 and at least electromagnetic actuator 178. The controller 179 may obtain from the distance sensor 200 a distance signal corresponding to the distance X between the distance sensor 200 and the ferromagnetic element 150. Based on the acquired distance signal, the controller 179 outputs an actuator signal corresponding to the target actuator force to be applied by the electromagnetic actuator 178.

[0038] In accordance with an embodiment of the present disclosure, which may be combined with other embodiments described herein, the controller 179 is configured to control closed loop control of at least one electromagnetic actuator to control the distance to the ferromagnetic element 150. can be configured for closed-loop control. For example, the controller 179 may implement a closed loop control mechanism to maintain the target distance. The closed loop control mechanism can include a PI controller, a PID controller, or any other closed loop controller in the art. The closed loop control mechanism may take at least one distance signal as input and generate a control signal for the at least one electromagnetic actuator as an output. The closed loop control mechanism can be configured to receive additional input signals. For example, the estimated current signal of at least one electromagnetic actuator can be used as an additional input signal.

[0039] As exemplarily shown in FIGS. 2A and 2B, the controller 179 may be a component of the floating unit 175. In this case, each floating unit 175 of the plurality of floating units 170 may each have a separate controller 179 that can independently control each floating unit 175. Optionally, each separate controller 179 disposed in each flotation unit 175 may be electrically attached to a control unit 130 as illustrated by way of example in FIG. 1. Alternatively, the controller 179 may be a component of the control unit 130, with each controller 179 for each floating unit 175 of the plurality of floating units 170 having a single control unit 130. Is incorporated).

[0040] According to embodiments of the present disclosure, which may be combined with other embodiments described herein, the injury unit 175 further includes at least a distance sensor 200. As exemplarily shown in FIG. 2A, the floating unit 175 may include two distance sensors 200 arranged on both sides of the electromagnetic actuator 178. The number of distance sensors 200 may be at least one distance sensor for each electromagnetic actuator 178, in particular two distance sensors 200 for each electromagnetic actuator 178.

[0041] The distance sensor 200 may include at least one transducer, which at least one transducer changes its output voltage in response to a magnetic field. For example, the distance sensor 200 may include a Hall effect sensor or a giant magnetoresistive (GMR) sensor. The distance sensor 200 is configured to detect the magnetic field of the ferromagnetic element 150 such that the distance X between the distance sensor 200 and the ferromagnetic element 150 can be determined. Thus, the distance sensor 200 can be used to contactlessly determine the distance between the carrier 110 to which the ferromagnetic element 150 is attached and the floating unit 175. Also, because the magnetic field of the ferromagnetic element 150 is detected, the presence of non-ferromagnetic elements between the distance sensor 200 and the ferromagnetic element 150 does not interfere with the operation of the distance sensor 200.

[0042] The distance sensor 200 may be located at an appropriate position to reliably measure the distance X to the ferromagnetic element 150. The distance sensor 200 can be mounted to the floating unit 175 or can be positioned within the floating unit 175. As exemplarily shown in FIGS. 2A and 2B, the distance sensor 200 may be positioned inline with the electromagnetic actuator 178. In order to achieve reliable and high performance control of the floating unit 175, colocation of the sensor and actuator in the sensor / actuator pair is desirable. Thus, it is desirable for the distance sensor 200 to be positioned very close to the electromagnetic actuator 178. In addition, positioning the distance sensor 200 very close to the electromagnetic actuator 178 has the additional effect of enabling the floating unit 175 to be more compact.

[0043] However, since the electromagnetic actuator 178 generates an electromagnetic field to float the carrier 110, positioning the distance sensor 200 very close to the electromagnetic actuator 178 is problematic. The stray magnetic fields generated by the electromagnetic actuator 178 can be detected by the distance sensor 200, resulting in undesirable cross-coupling with the electromagnetic actuator 178. This cross-coupling due to stray magnetic fields affects the reliable determination of the distance X between the distance sensor 200 and the ferromagnetic element 150, and thus the reliable determination of the distance between the carrier and the magnetic levitation system. Influences decisions

[0044] Reference is now made to FIGS. 3A and 3B showing side cross-sectional views of distance sensor 200 in accordance with embodiments of the present disclosure. Here, a distance sensor 200 is provided for measuring the distance X to the ferromagnetic element 150. The distance sensor 200 includes at least a first permanent magnet element 201, at least a first hall element 203 and at least a second hall element 204, the first permanent magnet element 201 having a first magnetic field ( 205). First and second, such that the direction of the first magnetic field 205 in the position of the first hole element 203 is substantially opposite to the direction of the first magnetic field 205 in the position of the second hole element 204. Hall elements 203 and 204 are oriented.

[0045] The second magnetic field 206 may be generated by the electromagnetic actuator 178 as an undesirable effect of floating the carrier 110. The second magnetic field 206 may comprise a floating magnetic field. Since the magnitude of the second magnetic field 206 depends on the flotation force applied to the carrier 110, the effect of the second magnetic field 206 on the distance sensor 200 is the electromagnetic actuator 178 and the distance sensor 200. Creates undesirable cross-linking between. By providing the distance sensor 200 according to the present disclosure, this undesirable cross-coupling can be compensated for.

[0046] Providing the distance sensor 200 with at least the first permanent magnet 201 and the first and second Hall elements 203, 204 may be distanced from the ferromagnetic element 150 by detecting the first magnetic field 205. While it is possible for the distance X between the sensors 200 to be determined, it is also possible for the second magnetic field 206 to be compensated for. The first magnetic field 205 generates a positive voltage component across the first hole element 203 and a negative voltage component across the second hall element 204. On the other hand, the second magnetic field 206 generates positive voltage components across both the first and second hall elements 203 and 204. The first and second Hall elements 203 and 204 by the second magnetic field 206 are subtracted by subtracting the voltage generated by the second Hall element 204 from the voltage generated by the first Hall element 203. The voltage components generated across the phase cancel and the voltage components generated across the first and second Hall elements 203 and 204 by the first magnetic field 205 are maintained.

[0047] The first and second Hall elements 203 and 204 generate a voltage based on the magnetic field applied to them. The first and second hall elements 203, 204 are positioned such that the first magnetic field 205 induces a voltage at the first and second hall elements 203, 204. The strength of the first magnetic field 205 is influenced by the presence of the ferromagnetic element 150, such that when the ferromagnetic element 150 is closer to or farther away from the distance sensor 200, the first magnetic field 205 is in between. Difference occurs. By positioning the hall elements 203, 204 such that the first magnetic field 205 generates a voltage at the hall elements 203, 204, the distance between the distance sensor 200 and the ferromagnetic element 150 can be measured. have.

[0048] The first magnetic field 205 is generated by at least the first permanent magnet element 201. First, referring to the embodiment illustrated by way of example in FIG. 3A, the distance sensor 200 includes a first permanent magnet element 201. The magnetic flux direction on one side of the distance sensor 200 is in the first flux direction away from the ferromagnetic element 150 and the magnetic flux direction on the other side of the distance sensor 200 is toward the ferromagnetic element 150. The first permanent magnet element 201 is positioned so that a magnetic field loop is created in the direction. The distance sensor 200 can further include core elements 202 positioned to direct the first magnetic field 205. The first and second hole elements 203, 204 have a first hole element 203 in the region of the magnetic flux in the first flux direction and the second hole element 204 in the magnetic flux in the second flux direction. Is positioned in the first magnetic field 205 such that it is in the region of.

[0049] An alternative arrangement is shown by way of example in FIG. 3B. In this embodiment, a first permanent magnet element 201a and a second permanent magnet element 201b are provided. The magnetic flux direction on one side of the distance sensor 200 is in the first flux direction away from the ferromagnetic element 150 and the magnetic flux direction on the other side of the distance sensor 200 is toward the ferromagnetic element 150. The polarities of the first and second permanent magnet elements 201a, 201b are arranged opposite to each other so that a magnetic field loop is created in the direction. The distance sensor 200 can further include a core element 202 positioned to direct the first magnetic field 205. The first and second hole elements 203, 204 have a first hole element 203 in the region of the magnetic flux in the first flux direction and the second hole element 204 in the magnetic flux in the second flux direction. Is positioned in the first magnetic field 205 such that it is in the region of.

[0050] At least first permanent magnet elements 201 may be included in a plurality of permanent magnet elements. For example, distance sensor 200 may include at least two first permanent magnet elements, or may include at least two first permanent magnet elements and at least two second magnetic elements. The plurality of permanent magnet elements are Halbach, such that the magnetic field generated by the plurality of permanent magnet elements is strong on the side facing the ferromagnetic element 150 and weak on the side opposite the ferromagnetic element 150. It can be oriented to form a (Halbach) array. Halbach arrays do not create a magnetic field on the rear surface of the Halbach array, so that other components located within the floating unit may be less susceptible to conventional magnetic elements compared to conventional magnetic elements. It is advantageous to the extent that it is affected by the first magnetic field.

[0051] According to embodiments of the present disclosure, the first and second Hall elements 203 and 204 may be configured such that the first magnetic field 205 generates a positive voltage at the first and second Hall elements 203 and 204. Are oriented opposite each other. This means that the first Hall element 203 positioned in the region of the magnetic flux in the first flux direction is oriented in the first flux direction and the second Hall element 204 positioned in the region of the magnetic flux in the second flux direction is It means that the first and second hole elements 203, 204 are oriented such that they are oriented in the second flux direction. Thus, in the side cross-sectional views shown in FIGS. 3A and 3B, the first Hall element 203 is oriented upward and the second Hall element 204 is oriented downward.

[0052] When the first and second Hall elements 203 and 204 are oriented opposite to each other, the first magnetic field 205 may cause the first Hall element 203 and the second to be substantially equal to each other. Generate positive voltages at both Hall elements 204. However, the second magnetic field 206 generates a positive voltage in one of the first or second hole elements 203, 204 such that the magnitudes of the respective voltages are substantially equal to each other and the first and second holes. Generate a negative voltage on the other of the elements 203, 204. Accordingly, the voltages generated by the first magnetic field 205 are maintained and the voltages generated by the second magnetic field 206 are canceled out of the second magnetic field 206 relative to the output voltage of the distance sensor 200. To compensate for the measured voltage of any effect, the voltages generated by each of the first and second Hall elements 203, 204 can be added.

[0053] As an alternative embodiment, the first and second Hall elements 203 and 204 are in the same direction as each other such that the first magnetic field 205 generates a positive voltage at one Hall element and a negative voltage at the other Hall element. Can be oriented. Thus, in the side cross-sectional views shown in FIGS. 3A and 3B, in this case, the first and second hole elements 203, 204 are both oriented upwards or both downward.

[0054] When the first and second hole elements 203 and 204 are oriented in the same direction as each other, the first magnetic field 205 may be formed at the first hole element 203 such that the magnitudes of the respective voltages are substantially the same as each other. Generate a positive voltage and generate a negative voltage at the second Hall element 204. However, the second magnetic field 206 generates a positive voltage at both the first and second hall elements 203, 204 such that the magnitudes of the respective voltages are substantially equal to each other. Accordingly, the voltages generated by the first magnetic field 205 are maintained and the voltages generated by the second magnetic field 206 are canceled out of the second magnetic field 206 relative to the output voltage of the distance sensor 200. To compensate for the measured voltage of any effect, the voltages generated by each of the first and second Hall elements 203, 204 can be subtracted.

[0055] By configuring the distance sensor 200 in accordance with the present disclosure, stray magnetic fields can be compensated. Floating magnetic fields can be generated, for example, by an electromagnetic actuator, a magnetic element on a substrate carrier, or a cathode target. Compensating the floating magnetic fields enables the distance sensor 200 to be positioned closer to the electromagnetic actuator, so that improved performance of the magnetic levitation system can be achieved through colocation of the sensor and the actuator. In addition, by compensating the floating magnetic fields, the distance sensor 200 can produce a more reliable and accurate distance measurement, so that the distance between the carrier and the magnetic levitation system can be maintained more reliably and more accurately.

[0056] According to an embodiment of the present disclosure, which may be combined with other embodiments described herein, the controller 179 shown in FIGS. 2A and 2B is generated by at least one electromagnetic actuator and has at least one distance. It may be configured to compensate for stray magnetic fields acting on the sensor. Controller 179 may be electrically attached to at least one distance sensor 200 such that controller 179 may receive first and second signals, respectively, from the first and second hall elements. The controller 179 may be configured to subtract the first and second signals from each other such that signal components generated by the stray magnetic field generated by the at least one electromagnetic actuator are compensated for.

[0057] According to a third embodiment of the present disclosure, a method for measuring the distance to a ferromagnetic element is provided. The method includes providing a distance sensor comprising a first Hall element and a second Hall element, detecting a first signal of the first Hall element and a second signal of the second Hall element, and from the first signal; Subtracting two signals.

[0058] Reference is now made to FIG. 4, which shows a flow diagram for a method 500 for measuring distance to a ferromagnetic element in accordance with embodiments of the present disclosure. The method 500 begins at start 510.

[0059] At block 511, a distance sensor is provided that includes a first hall element and a second hall element. The distance sensor may be a distance sensor in accordance with embodiments described herein, which may measure the distance to the ferromagnetic element. The distance sensor may be provided, for example, in proximity to the electromagnetic actuator. Unwanted stray magnetic fields generated by electromagnetic actuators can affect the distance sensor, causing cross-coupling between the electromagnetic actuator and the distance sensor.

[0060] At block 512, a first signal of the first Hall element is detected, while at block 513, a second signal of the second Hall element is detected. Respectively, the first and second signals of the first and second Hall elements may include components of the stray magnetic field signal and the ranging signal, respectively. The ranging signal components of each of the first and second signals may be substantially equal in magnitude but opposite in polarity, while the floating magnetic field signal components of each of the first and second signals may be substantially equal in magnitude and , May have the same polarity.

[0061] At block 514, the first signal of the first Hall element and the second signal of the second Hall element are subtracted from each other. Since the floating magnetic field signal components of each of the first and second signals are substantially the same size and have the same polarity, subtracting the first and second signals from each other causes the floating magnetic field signal components of the first and second signals to be subtracted. Offset each other. Thus, the stray magnetic field signal components can be compensated for, resulting in a distance signal that remains unaffected by unwanted stray magnetic fields. Finally, method 500 terminates at termination 520.

[0062] According to further embodiments, which may be combined with other embodiments described herein, the distance sensor provided at block 511 may further comprise at least a first permanent magnet element for generating a first magnetic field and , The direction of the first magnetic field in the position of the first hole element is substantially opposite to the direction of the first magnetic field in the position of the second hall element. Alternatively, the distance sensor provided at block 511 may further include at least a first permanent magnet element and at least a second permanent magnet element for generating a first magnetic field, the first in the position of the first hole element. The direction of the first magnetic field is substantially opposite to the direction of the first magnetic field at the position of the second hole element. Thus, the first magnetic field causes the first Hall element to generate the first ranging signal component and the second Hall element to generate the second ranging signal component, the polarity of the first ranging signal component being second The polarity of the ranging signal component is opposite. For example, the first magnetic field causes the first Hall element to generate a positive voltage component and the second Hall element to generate a negative voltage component. The magnitudes of the first and second ranging signal components generated by the first and second hall elements, respectively, may be substantially the same, such that at block 514, the first and second holes and the first and second hall elements are the same. When the two signals are each subtracted from each other, the first and second ranging signal components do not cancel each other, and the first and second floating magnetic field components are compensated for. Thus, a distance signal can be generated that remains unaffected by the effects of stray magnetic fields.

[0063] Method 500 may be performed using a controller. For example, referring again to FIGS. 2A and 2B, the method 500 may be performed by a controller 179, which may be a component of the flotation unit 175. Controller 179 may be electrically attached to at least distance sensor 200, such that controller 179 receives a first signal and a second signal as input.

[0064] As discussed above, one aspect of the magnetic levitation system is to incorporate electromagnetic actuators and distance sensors into the levitation unit to achieve a minimized size of the magnetic levitation system and improved control behavior through colocation of actuators and sensors. Are positioned closer to each other. One undesirable effect on closer proximity between electromagnetic actuators and distance sensors is that the stray magnetic fields generated by the electromagnetic actuators introduce a cross-coupling effect with the distance sensors. Embodiments described herein solve this problem by subtracting their signals, eg, using first and second Hall elements to compensate for floating magnetic fields.

[0065] However, when the distance sensor is positioned much closer to the electromagnetic actuators, an additional undesirable effect is that the stray magnetic field may not affect the first and second Hall elements evenly within the distance sensor. Is introduced. For example, the curvature of the floating magnetic field may be higher in the region where the distance sensor is positioned, or the magnitude of the floating magnetic field may not be uniform. These effects are particularly problematic for distance sensors, which can be positioned, for example, between electromagnetic actuators. In such cases, the first and second magnetic field signal components may not be sufficiently the same in magnitude so that the second magnetic field signal is fully compensated through subtraction. Thus, further compensation of these effects may be advantageous.

[0066] Reference is now made to FIG. 5, which shows a flow diagram for a method 501 for measuring the distance to a ferromagnetic element. According to embodiments of the present disclosure, which may be combined with other embodiments described herein, the method 501 detects a coil current of at least one electromagnetic actuator and is generated by the at least one electromagnetic actuator. Further comprising using coil current to estimate the magnetic flux, and compensating for the wrong component of the distance signal measured by the distance sensor. The method 501 begins at start 510.

[0067] The method 501 comprising blocks 511, 512, 513 and 514 according to the method 500 described above, further comprises detecting, at block 515, the coil current of the at least one electromagnetic actuator. do. The coil current of the electromagnetic actuator is proportional to the magnetic flux produced by the electromagnetic actuator. The coil current may be detected from a current signal sent to the electromagnetic actuator or by using a current sensor configured to measure the current in the coil of the electromagnetic actuator.

[0068] Also at block 516, the magnetic flux generated by the at least one electromagnetic actuator is estimated. Estimation of the generated magnetic flux is based on the coil current of at least one electromagnetic actuator as detected at block 515. Estimating the magnetic flux includes generating a magnetic flux compensation signal that can be used to compensate for erroneous components of the distance signal generated by the distance sensor.

[0069] Finally, at block 517, the wrong component of the distance signal measured by the distance sensor is compensated. Compensation is performed by subtracting the magnetic flux compensation signal generated at block 516 from the distance signal detected by the distance sensor, so that cross-coupling between the electromagnetic actuator and the distance sensor, which has not yet been compensated by block 514, is achieved. Additional effects of are compensated for.

[0070] Performing method 501 as described above enables further compensation of floating magnetic fields, such as non-uniform or high curvature floating magnetic fields, or floating magnetic fields from adjacent electromagnetic actuators, thereby providing distance The sensors can be positioned much closer to the electromagnetic actuators, further improving the performance of the magnetic levitation system.

[0071] According to embodiments of the present disclosure, which may be combined with other embodiments described herein, estimating the magnetic flux at block 516 may be based on the magnitude and / or frequency of the coil current. Calculating the model. The coil current may, for example, induce eddy currents in the housing 176 or may produce a given flux magnitude that depends on frequency. Ferromagnetic element 150 may also be a non-laminating element, which may introduce frequency dependency. The model may include a predetermined or pre-calculated model of the magnetic flux generated by the electromagnetic actuator for a given coil current magnitude and / or frequency. For example, the model may include a lookup table of pre-computed values. Alternatively, the model can be calculated in real time based on a mathematical approximation of the magnetic flux generated by the electromagnetic actuator for a given coil current magnitude and / or frequency.

[0072] The model of magnetic flux can be determined by measuring the magnetic flux behavior of the electromagnetic actuator in response to the applied coil current and by determining its effect on the distance signal. The ferromagnetic element is fixed at a known distance from the distance sensor and a coil current is applied to the electromagnetic actuator to produce a distance signal from the distance sensor. Changing the coil current applied to the electromagnetic actuator produces a change in magnetic flux, which changes the distance signal from the distance sensor under the influence of the magnetic flux. By measuring the change in the distance signal based on the coil current, a model for estimating the effect of the magnetic flux of the electromagnetic actuator on the distance signal based on the coil current can be calculated.

[0073] The model may consider additional parameters for estimating the magnetic flux generated by the at least one electromagnetic actuator. For example, the model may include parameters related to coil current of at least one neighboring electromagnetic actuator. If the electromagnetic actuator is positioned very close to the neighbors of the electromagnetic actuator, the stray magnetic flux generated by the neighboring electromagnetic actuators may also be cross-coupled with the neighboring distance sensors. Thus, the wrong component of the distance signal produced by the distance sensor, caused by the stray magnetic flux acting on the distance sensor, can be further compensated.

[0074] According to embodiments of the present disclosure, which may be combined with other embodiments described herein, estimating magnetic flux is performed on a digital signal processor. Digital signal processors typically include analog-digital converters (ADCs), digital signal processing units, and digital-analog converters (DACs), so that analog signals are manipulated in real time. Make it possible. The digital signal processor may be a separate component provided in the flotation unit or may be integrated in a controller for the flotation unit. Performing estimation of the magnetic flux on the digital signal processor enables real-time estimation of the magnetic flux, allowing for faster acquisition of the distance signal and further maintaining the target distance between the carrier and the injury system. Enables high performance

[0075] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from the basic scope of the present disclosure, the scope of the present disclosure being set forth in the following claims Determined by

Claims (16)

As a distance sensor 200 for measuring the distance to the ferromagnetic element 150,
At least first permanent magnet elements 201, 201a;
At least a first hall element 203; And
At least a second Hall element 204,
The first permanent magnet elements 201, 201a create a first magnetic field 205, and the direction of the first magnetic field 205 in the position of the first hole element 203 is the second hall element. Substantially opposite the direction of the first magnetic field 205 in the position of 204,
Distance sensor 200. According to claim 1,
Further comprising at least a second permanent magnet element 201b arranged parallel to the first permanent magnet element 201a and having a polarity opposite to the first permanent magnet element 201a,
The first permanent magnet element 201a and the second permanent magnet element 201b generate the first magnetic field 205,
Distance sensor 200. The method according to claim 1 or 2,
The first Hall element 203 and the second Hall element 204 are configured such that the first magnetic field 205 generates a positive voltage at the first Hall element 203 and the second Hall element 204. Oriented opposite to each other,
Distance sensor 200. Magnetically levitated system 100 for magnetically levitating a ferromagnetic element 150,
At least one electromagnetic actuator 178; And
At least one distance sensor 200 according to any one of claims 1 to 3,
The at least one distance sensor 200 is configured to measure the distance X to the ferromagnetic element 150,
Magnetic levitation system (100). The method of claim 4, wherein
Further comprising controllers 130, 179 configured for closed-loop control of the at least one electromagnetic actuator 178 to control the distance X to the ferromagnetic element 150,
Magnetic levitation system (100). The method of claim 5,
The controllers 130, 179 are configured to compensate magnetic fields generated by the at least one electromagnetic actuator 178 and acting on the at least one distance sensor 200,
Magnetic levitation system (100). The method according to any one of claims 4 to 6,
The at least one electromagnetic actuator 178 is configured to transport the ferromagnetic element 150 in a transport direction 192,
Magnetic levitation system (100). The method according to any one of claims 4 to 7,
The ferromagnetic element is a substrate carrier 110,
Magnetic levitation system (100). The method according to any one of claims 5 to 8,
The at least one electromagnetic actuator 178, the at least one distance sensor 200 and the controller 179 are included in an airtight housing 176,
Magnetic levitation system (100). The method according to any one of claims 4 to 9,
The magnetic levitation system 100 is configured for operation in a vacuum,
Magnetic levitation system (100). A method for measuring the distance X to the ferromagnetic element 150,
Providing a distance sensor (200) comprising a first hall element (203) and a second hall element (204);
Detecting a first signal of the first hall element (203) and a second signal of the second hall element (204); And
Subtracting the second signal from the first signal;
A method for measuring the distance X to the ferromagnetic element 150. The method of claim 11, wherein
The distance sensor 200 further includes at least first permanent magnet elements 201, 201a for generating a first magnetic field 205,
The direction of the first magnetic field 205 in the position of the first hole element 203 is substantially opposite to the direction of the first magnetic field 205 in the position of the second hole element 204,
A method for measuring the distance X to the ferromagnetic element 150. The method of claim 11 or 12,
Detecting a coil current of at least one electromagnetic actuator 178;
Estimating the magnetic flux generated by the at least one electromagnetic actuator (178) using the coil current; And
Compensating for the erroneous component of the distance signal measured by the distance sensor 200,
A method for measuring the distance X to the ferromagnetic element 150. The method of claim 13,
Estimating the magnetic flux includes calculating a model of the magnetic flux based on the magnitude and / or frequency of the coil current.
A method for measuring the distance X to the ferromagnetic element 150. The method according to claim 13 or 14,
Estimating the stray magnetic flux is performed on a digital signal processor,
A method for measuring the distance X to the ferromagnetic element 150. As the use of the distance sensor 200 according to any one of claims 1 to 3 in the magnetic levitation device 100,
The distance sensor 200 is configured to measure the distance X to the injured body,
Use of distance sensor 200.

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